The Tower (1985)

'Lola' is the entirely self-sufficient, computerized security system for the Sandawn corporation. When Lola is left in charge of the building for one night, she decides the late-working employees and their acquaintances would make an excellent source of energy for her systems to function on. Seeking out the 'heat sources', the remaining people trapped in the building must find a way to shut down Lola before the morning.